From: Pingfan Liu <kernelfans@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Pingfan Liu <kernelfans@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rafael@kernel.org>
Subject: [PATCHv2] genirq/PM: Make for_each_irq_desc() safe of irq_desc release
Date: Wed, 27 Apr 2022 14:03:38 +0800 [thread overview]
Message-ID: <20220427060338.7276-1-kernelfans@gmail.com> (raw)
In-Reply-To: <20220420140521.45361-7-kernelfans@gmail.com>
First, this is a suspicion of the code, not a really encountered bug.
*** The scenario ***
Two threads involved
threadA "hibernate" runs suspend_device_irqs()
threadB "rcu_cpu_kthread" runs rcu_core()->rcu_do_batch(), which releases
object, let's say irq_desc
Zoom in:
threadA threadB
for_each_irq_desc(irq, desc) {
get irq_descA which is under freeing
--->preempted by rcu_core()->rcu_do_batch() which releases irq_descA
raw_spin_lock_irqsave(&desc->lock, flags);
//Oops
And since in the involved code piece, suspend_device_irqs() runs in a
preemptible context, and there may be more than one thread at this
point. So the preemption can happen.
*** The fix ***
Since there is a blockable synchronize_irq() inside the code piece,
resorting to irq_lock_sparse() to protect the irq_desc from
disappearing.
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
To: linux-kernel@vger.kernel.org
---
v1 -> v2: improve commit log
kernel/irq/pm.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/irq/pm.c b/kernel/irq/pm.c
index ca71123a6130..4b67a4c7de3c 100644
--- a/kernel/irq/pm.c
+++ b/kernel/irq/pm.c
@@ -133,6 +133,7 @@ void suspend_device_irqs(void)
struct irq_desc *desc;
int irq;
+ irq_lock_sparse();
for_each_irq_desc(irq, desc) {
unsigned long flags;
bool sync;
@@ -146,6 +147,7 @@ void suspend_device_irqs(void)
if (sync)
synchronize_irq(irq);
}
+ irq_unlock_sparse();
}
EXPORT_SYMBOL_GPL(suspend_device_irqs);
@@ -186,6 +188,7 @@ static void resume_irqs(bool want_early)
struct irq_desc *desc;
int irq;
+ /* The early resume stage is free of irq_desc release */
for_each_irq_desc(irq, desc) {
unsigned long flags;
bool is_early = desc->action &&
--
2.31.1
next prev parent reply other threads:[~2022-04-27 6:04 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-20 14:05 [PATCH 0/9] trival fix or improvement about irq_desc access Pingfan Liu
2022-04-20 14:05 ` [PATCH 1/9] irq/irqdesc: put the lock at the exact place in irq_sysfs_init() Pingfan Liu
2022-04-20 14:05 ` [PATCH 2/9] irq/irqdesc: change the name of delete_irq_desc() to irq_delete_desc() Pingfan Liu
2022-04-20 14:05 ` [PATCH 3/9] irq/manage: remove some unreferenced code Pingfan Liu
2022-04-20 20:56 ` Miguel Ojeda
2022-04-20 14:05 ` [PATCH 4/9] s390/irq: utilize RCU instead of irq_lock_sparse() in show_msi_interrupt() Pingfan Liu
2022-04-20 18:16 ` Heiko Carstens
2022-04-21 3:36 ` Pingfan Liu
2022-04-21 11:42 ` Heiko Carstens
2022-04-22 9:56 ` Pingfan Liu
2022-04-22 10:02 ` [PATCHv2] " Pingfan Liu
2022-04-25 11:39 ` Heiko Carstens
2022-04-20 14:05 ` [PATCH 5/9] x86/irq: place for_each_active_irq() in rcu read section Pingfan Liu
2022-04-20 14:05 ` [PATCH 6/9] pm/irq: make for_each_irq_desc() safe of irq_desc release Pingfan Liu
2022-04-20 16:23 ` Rafael J. Wysocki
2022-04-21 3:31 ` Pingfan Liu
2022-04-21 10:57 ` Rafael J. Wysocki
2022-04-22 10:43 ` Pingfan Liu
2022-04-27 6:03 ` Pingfan Liu [this message]
2022-04-20 14:05 ` [PATCH 7/9] irq: remove needless lock in takedown_cpu() Pingfan Liu
2022-04-21 16:11 ` Thomas Gleixner
2022-04-25 2:57 ` Pingfan Liu
2022-04-25 9:43 ` Thomas Gleixner
2022-04-27 6:01 ` Pingfan Liu
2022-04-20 14:05 ` [PATCH 8/9] irq: make irq_lock_sparse() independent of CONFIG_SPARSE_IRQ Pingfan Liu
2022-04-20 14:05 ` [PATCH 9/9] irq/irqdesc: rename sparse_irq_lock to bitmap_lock Pingfan Liu
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